I barely remember a story or movie about a man (or maybe woman) who had 2 lives: when he goes to sleep he wakes up in his dream, and when he falls asleep in his dream he wakes up in his real life. But he couldn't tell which life is his dream and which one is reality. As I recall, he was a scientist and he started taking notes and sending letters and messages to himself.
I know it is not much but does it sound familiar to anyone?
Edit: I remember now that I saw this on tv around 10 years ago. Perhaps the movie was from Poland or Checkslovakia or other central/eastern european country.
Edit2: A friend of mine told me that he also saw this movie. As he remembers it was a sequel of Accumulator 1 and it was called "akumulátor dvá", but can't find it on the internet.